It is well known that air conditioning units are relatively inexpensive. They can often be purchased for amounts even as low as $30 in some developing countries; domestic prices can be found as being as low as around $150. In contrast, refrigeration systems that are employed in commercial settings tend to be expensive and have relatively high power demands and installation requirements. Accordingly, it is seen that there is a need for a mechanism, which is capable of converting an inexpensive air-conditioning unit so that it operates as the core of a refrigeration system.
However, it is not well known that air conditioning units are typically designed to shut down their compressor operations when it gets too cold. For the typical room size air conditioner, this temperature is around 64° F. but may be as low as 60° F. For example, Frigidaire® has made an air conditioner unit in which a temperature sensor is disposed in thermal contact with the coils of the device. When the coils become “too” cold, the compressor is shut down. One of the reasons that they do this is to control the viscosity of the refrigerant since efficiency is adversely affected by having the refrigerant pass through an expansion valve (orifice) which is too small relative to the fluid's viscosity. Later models of the Frigidaire® units eliminate this temperature sensor and instead rely solely on the room air temperature sensor which is still used to shut the compressor down at a temperature of around 60° F.
It is also noted that not all air conditioning units employ a thermistor type of temperature sensor. Again, this temperature sensor is for room air and is intended to determine the point at which the unit shuts down to avoid further cooling. Some A/C units, such as those typified by units installed in recreational vehicles, employ a long copper capillary tube as part of an analog design. These units typically employ an integral switch assembly with a rotatable analog setting knob which controls the lower cutoff temperature based on temperatures to which the relatively lengthy capillary tube is exposed. Such units are found in recreational vehicles (RVs) and in older air conditioners as well as in inexpensive air conditioners sold in developing countries. The present invention includes an embodiment that is compatible with this A/C design as well and allows RV air conditioners to operate large truck cooling systems at a cost of around $2,400 instead of the present cost of around $14,000.
It is further noted that there is a significant need for inexpensive refrigeration systems. In particular, farmers would very much like to have an inexpensive method for keeping their produce and crops at reduced temperatures were for storage and for longer shelf life. Additionally individuals such as florists, restaurants, and grocery stores would also benefit from having inexpensive refrigeration systems. Furthermore, as desirable as these systems are in the United States, they are immeasurably more desirable in other parts of the world where refrigeration is at a premium but which is nonetheless a necessity because of the elevated temperatures of the climates in these regions.
In addition to the fact that refrigeration systems are expensive, it is also the case that such systems are very demanding in terms of their electrical power requirements. It is therefore seen that there is also a need for cooling systems that require less electricity than is consumed by conventional cooling systems which the current invention in combination with a standard window air conditioning unit is capable of doing.
One of the problems with using a conventional air-conditioning unit as part of a refrigeration system is that such units are designed with specific controlling features in mind, which limit their operations, cycle duration and their cooling capabilities. For example, the control units for a conventional window air conditioner are set so that the units turn off at a relatively high sensed temperature. Nonetheless, for purposes of using a conventional air-conditioning unit as the core of a refrigeration system, these air conditioners, with their conventional control units, are set up so that it is always far from the case that humidity is allowed to condense on the fins of the unit in the form of ice. In short, in their normal mode of operation, conventional air-conditioning systems are designed to cut out at a relatively high temperature. It is therefore seen that in their off-the-shelf state, these units are not capable of operating as refrigeration units. The adapter units of the present invention provide a retrofit mechanism which extends the range of operation for a conventional air conditioning unit. This is found to be particularly advantageous in relatively small and inexpensive window units.